from datetime import date, datetime
class User:

    def __init__(self, name, birthday):
        self.name = name
        self.birthday = birthday
        self.age = 0


    @property
    def age(self):
        return datetime.now().year - self.birthday.year

    @age.setter
    def age(self, value):
        self._age = value


    def __getattr__(self, item):
        return 'there is no level'

if __name__ == '__main__':
    user = User('yaoxin', date(year=1981, month=11, day=1))
    print(user.level)
